The present invention relates to a printing sheet that enables the production of an accordion fold type book assembly. In particular, in case of a printing section composed of valley folds and mountain folds formed at regular intervals, although the other three faces except for the valley fold of the printing section may be formed into cutting faces, if the opposite printing sections of the printing sheet join together in an accordion fold manner those cutting faces of the printing section are not deformed but folded neatly, creating a precise joint. Also, the other faces except for the valley fold of the printing section are cut into cutting faces such that the opposite printing sections joined together have a uniform thickness so as to provide the book assembly with orderly and tidy outer end faces and turning the pages of the book can be done in a gentle manner. Accordingly, the printing sheet of the present invention can be produced easily by anyone without using exclusive tools such as a copying or cutting machine and a book assembly can be produced using the same.